code: def lookup(name, base, override_name=None):
      """Looks up a subclass of a base class from the registry.
  
      Looks up a subclass of a base class with name provided from the
      registry. Returns the registered subclass if found, None otherwise.
  
      Args:
        name: Name to look up from the registry.
        base: The base class of the subclass to be found.
        override_name: string to override the name of the instance.
  
      Returns:
        Subclass of the name if found, None otherwise.
      """
      basename = base.__name__
      if basename not in _registries:
          return None
      registry = _registries[basename]
      if name not in registry:
          return None
      init_args = registry[name][_INIT_ARGS]
      if override_name:
          init_args.update({"name": override_name})
      if init_args is not None:
          return registry[name][_TYPE_TAG](**init_args)
      return registry[name][_TYPE_TAG]
  
file_path: model_search/model_search/registry.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import inspect
  import traceback
  from absl import logging
label_desc: Use image node_id 2 for calling a global function with example usage: lookup(name, base, override_name) and returns: registry, None, None, registry